Articles by Peitsa Mikola

The fungal symbiont of ectendomycorrhizae is an ascomycete Wilcoxina (Tricharina) mikolae Yang & Korf. It forms ectendomycorrhizae with Pinus and Larix and ectomycorrhizae with Abies, Picea, Pseudotsuga and Tsuga. It is common in forest nurseries around the world. After transplanting the seedlings into natural forest soil, indegenous fungi rapidly replace Wilcoxina. Inoculation of nursery soil with Wilcoxina is recommended if soil has been sterilized or for other reasons mycorrhizal fungi are absent.

The PDF includes a summary in Finnish.

• Mikola, E-mail: pm@mm.unknown

This article reviews experiments and practical experience of forest management by the selection system in Finland. In an experiment of 25-year duration the annual growth of uneven-aged Norway spruce (Picea abies (L.) H. Karst.) stands was only about 50% of the average annual yield of even-aged stands in normal rotation on the same site.

In Finland the selection system is applicable under exceptional conditions only, viz. In intensively managed park stands and, on the other hand, on very marginal sites, e.g. on peat bogs and mountains near the tree-line. Even normal silviculture, however, may include cuttings which somewhat resemble selection system, e.g. removal of standards or restoration of mismanaged forests.

The PDF includes a summary in English.

• Mikola, E-mail: pm@mm.unknown

This paper reviews the background documents and the final report of the United Nations Conference on Desertification, held in Nairobi, Kenya, in August/September of 1977. Deforestation for grazing or agriculture has often been the initial step towards desertification. Consequently, tree planting plays a central role in the reclamation of desertified areas. Shelterbelts and other tree plantations protect agricultural land, settlements and communications.

Tree plantations in arid zones need effective protection against grazing and other improper land use. This must be explained to political leaders and local people. As a long-term investment, it requires a high level of education to understand its ultimate usefulness, and also research to choose the best species and techniques for different climatic and soil conditions is needed. In addition, afforestation will contribute to the solution of energy problems. Fast growing trees, even with artificial irrigation, can be the most efficient and economical way to cover energy needs of rural people. To accomplish the task of reclamation of decertified areas, international cooperation and technical and economic support from industrial countries to developing countries is needed.

The PDF includes a summary in Finnish.

• Mikola, E-mail: pm@mm.unknown

Traditionally, European forest education has emphasized environmental conservation. Forest education reflects the needs of society. After the industrial revolution, rapidly growing forest industries needed an increasing amount of wood, and the emphasis of forestry education was on timber production on the basis of sustained yield, and on efforts for progressively raising yields.

The technical and economic development of the recent decades introduced two themes in the environmental content of forest education: 1) The changing role of forests in society increase importance of protection and recreational functions of forests, and 2) modern technology has caused great changes in the forestry itself. These changes have to be taken into account also in the forest education. The environmental content of forest education can be divided into two broad fields, the ecological basis and environmental influences of various forest operations, and forest management for non-production uses. In both fields university curricula include a) basic courses, obligatory for all forestry students, b) optional courses, and c) advanced courses for higher degrees.

The PDF includes a summary in Finnish.

• Mikola, E-mail: pm@mm.unknown

Peat industry is rapidly expanding in Finland. Consequently, during next decades peat will be removed from thousands of hectares. Because timber production probably is the most rational use of this area after the peat production has ended, some experiments of afforestation of such areas have already been conducted. This article reports results of two experiments which were started in Kihniö, Western Finland, in 1953 and 1964.

In the first experiment fertilization with wood ash proved very effective whereas seeding and planting without fertilization resulted in almost complete failure. In the second experiment, interplanting with grey alder (Alnus glutinosa L. Gaertn.) greatly promoted the growth of Scots pine (Pinus sylvestris L.). The effect of slight fertilization lasted a few years only. The reasons for the remarkable effect of alder need further research. Although alder is known as a nitrogen-fixing plant, its beneficial effect was most clearly seen in the K and P contents of pine needles. Inoculation with mycorrhizal fungi was beneficial but not necessary. Experiments hitherto show that afforestation of bogs after peat removal is possible although some additional measures like fertilization or interplanting with alder may be needed.

The PDF includes a summary in English.

• Mikola, E-mail: pm@mm.unknown

The article is a report of a study tour of five Finnish foresters in Germany on September 27 – October 2. 1971. As in most industrial countries, the recreation use of forests is rapidly expanding and, therefore, its needs are considered in the management of forests. Two examples of intensively used recreation forests are described, Schönbuch near Stuttgart and the Bavarian Forest National Park at the Czechoslovakian border. These forests are effectively used for both timber production and recreation at the same time. Some other effects of urbanization on forests also are discussed in the article.

The PDF includes a summary in English.

• Mikola, E-mail: pm@mm.unknown

The purpose of forestry has hitherto been seen mainly as economic conservation, i.e. the use and management of timber resources on a sustainable yield basis. Along with the rising standard of living, however, amenity values of the environment will become more appreciated, which means that forestry and forest industries will be concerned with conservation of immaterial resources of nature as well. Since inland lakes cover some 10% of the surface area of Finland, and forests occupy more than 70% of the land area, forests and lakes are essential constituents of the Finnish environment during both work and leisure.

The main task of the pulp and paper industry in conservation is the control of water pollution. Today some 10% of Finnish lakes are polluted. Pulp and paper industries contribute 75% of the total waste water load of the Finnish lakes. Increasing water pollution can be prevented by improved processing technology, waste water treatment, and economic use of industrial wastes. Thus, the waste water load of the lakes has not increased in the last 10 years, despite doubling of pulp and paper production. According to the prognoses, by the year 2000 the waste water load from pulp and paper industries will be reduced to one half or one fourth of the present level although the capacity will still be increasing.

In forest management more emphasis should be paid on the aesthetic and recreational values of forests. Along with increasing leisure the need for recreational areas is growing. Scenic and recreational aspects must be considered in the management of industrial forests, too. With wise management, high timber yield is compatible with the maintenance of an enjoyable environment. Good silviculture takes account of timber production, wildlife management and landscape architecture simultaneously. National forestry development programs must be based on the principle of the multiple use of forests.

The PDF includes a summary in English.

• Mikola, E-mail: pm@mm.unknown

This article is a review of an article ’Fundamental studies to improve production of Pinus radiata and other pines’ by Donald, D.G.M.

• Mikola, E-mail: pm@mm.unknown

Finnish tree species have adapted differently to heavy snow loads that occur especially in fell areas in Kuusamo and Salla as well as Maanselkä area in Sotkamo and Rautavaara in Northern Finland. Norway spruce (Picea abies Karst. L) is adapted better than Scots pine (Pinus sylvestris L.). The aim of this study was to investigate how crown and stem form of Norway spruce in the snow damage area of Maanselkä area differ from other areas in the same region.  

Relatively broad crown at the base of the stem, quickly tapering crown and narrow and even upper crown were typical for trees growing in the snow damaged areas. The higher the altitude is, the stronger tapering the crown is. The tapering begins usually in a height of 4-5 meters. Even the stem diameter begins to taper strongly at this height. In the areas where heavy snow does not cause snow damage, top of crown is broader. Also, in the snow damage areas the damaged trees seem to have broader crown shape than the trees with little damages.  

Height of the trees decreases in the snow damage areas compared to forests in lower altitudes, which can be caused both by wind and snow load. 

The article includes a German summary. 

• Mikola, E-mail: pm@mm.unknown

The differences between different types of mycorrhiza; endomycorrhiza, ectomycorrhiza and ectendomycorrhiza, and the use of the terms have been variable in the earlier research. Studied of mycorrhiza in Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) seedlings may suggest that the conditions affect which kind of mycorrhiza develops in the seedlings. This study is aimed mainly at finding out whether the difference of ectotrophic and ectendotrophic mycorrhizae depends on fungal symbionts or envirionmental conditions. Furthermore, the occurrence of ectendotrophic mycorrhiza in Finland under various conditions was studied, and experiments on the physiology and ecology of the mycorrhiza and the fungal partner were conducted.

The ectendotrophic mycorrhiza as described in this paper has proved to be very common on Scots pine in Finnish nurseries, but it was not found in Norway spruce seedlings. The results did not support the hypothesis presented in some earlier studies that ectendotrophic mycorrhiza is more parasitic than the other mycorrhizal fungi. The nursery survey showed that no correlation existed between the size and vigour of the seedlings and the presence of ectendotrophic mycorrhiza. Furthermore, greenhouse-grown seedlings with and without the fungus grew equally well. The type of mycorrhiza was, however, almost exclusively confined to young (1–3-years-old) seedlings and to nursery soils. The experiments indicates also that ectendomycorrhizal fungus has a very wide ecological amplitude in regard to light intensity, soil fertility, acidity, and humus content. It has, however, a weak competitive ability in natural forest soils against the indigenous fungal population. When the seedlings were transplanted from the nursery to forest soil, their mycorrhizal population was largely changed.

• Mikola, E-mail: pm@mm.unknown

Prescribed burning is a common silvicultural practice in northern Europe, intended to destroy the slash and ground vegetation and to reduce the thickness of the raw humus layer prior reforestation. The purpose of the experiments was to study whether there are any differences in the commencement and early development of mycorrhizal infection between burned and unburned areas. A clear-cutting area was burned on May 1961. The soil was rocky moraine, the forest type was Vaccinium type. Two weeks after burning Scots pine (Pinus sylvestris L.) was sown in patches.

According to the results, mycorrhizal infection took place on the unburned area earlier than on the burned. The difference was relatively small, perhaps 1–2 weeks. Although burning kills mycorrhizal fungi, it did not cause serious harm to the seedlings, on the contrary, the favourable influence of burning was more distinct. The high temperatures caused by the fire are restricted in the soil in a prescribed burning only a few centimetres deep. Although the mycorrhizal fungi are concentrated in a very thin surface layer of the soil, some mycorrhizae are situated deeper, and from there the fungi are able to infect roots and spread back to the surface layer. The fire also rises the pH of the soil, which can be harmful for mycorrhizal fungi. Even this effect, however, is limited to a thin surface layer.

The PDF includes a summary in Finnish.

• Mikola, E-mail: pm@mm.unknown
• Laiho, E-mail: ol@mm.unknown
• Eerikäinen, E-mail: je@mm.unknown
• Kuvaja, E-mail: kk@mm.unknown

Mycorrhizal association is a characteristic feature of the trees of the northern coniferous forests. The purpose of the present study was to determine what influence some fungicides and herbicides regularly used in Finnish nurseries have on formation and development mycorrhizal in Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) seedlings. The results are based mainly on field experiments in nurseries. First the initiation of mycorrhiza was described in untreated seedlings.

In the first growing season mycorrhizal infection commences fairly late even under normal conditions, i.e. 6–7 weeks after seeding and 3–4 weeks after the formation of the first short roots. Soil disinfectants are commonly used in nurseries before seeding, and they are supposed to evaporate or disintegrate in a few days or 1–2 weeks. In pure culture experiments mycorrhizal fungi proved several times more sensitive than parasitic and indifferent soil moulds to herbicides and fungicides, but in field experiments the delay of mycorrhizal infection caused by them does not seem to harm the seedlings. In the second summer differences of mycorrhizal relations between treated and control plots disappeared. Accordingly, the influence of biocides on mycorrhizae, when applied in the customary concentrations, does not extend beyond the first growing season.

Methyl bromide and SMDC retarded mycorrhiza formation distinctly, while formaldehyde and allyl alcohol had no effect. Apart from not retarding mycorrhizae, formaldehyde and allyl alcohol promoted seedling growth and favoured Trichoderma viride in the soil. Trichoderma is known to be antagonistic to many fungi.

The PDF includes a summary in Finnish.

• Laiho, E-mail: ol@mm.unknown
• Mikola, E-mail: pm@mm.unknown

This paper is a review on the silvicultural research in Finland, researchers and the main subject of the research within the previous 50 years. The task of silvicultural research is to serve forest management work and create a foundation for the practical operations, on one hand, and to answer to the constantly arising questions in the practice of forest management, on the other.

It can be said that the forestry as an independent branch of science began in 1909. At first the research was primarily biological, dealing with both the foundations and practices of silviculture. The main subjects are divided to forest sites and vegetation, biology of trees and stand, and methods of forest management.

The article is published in Finnish in separate PDF Acta Forestalia Fennica vol 70 no 3.

• Mikola, E-mail: pm@mm.unknown
• Kangas, E-mail: ek@mm.unknown
• Heikurainen, E-mail: lh@mm.unknown

This paper is a review on the silvicultural research in Finland, researchers and the main subject of the research within the previous 50 years. The task of silvicultural research is to serve forest management work and create a foundation for the practical operations, on one hand, and to answer to the constantly arising questions in the practice of forest management, on the other.  

Forestry as an independent branch of science began in 1909. At first the research was primarily biological, dealing with both the foundations and practices of silviculture. The main subjects are divided to forest sites and vegetation, biology of trees and stand, and methods of forest management. 

The article is published in English in separate PDF Acta Forestalia Fennica vol 70 no 4. 

• Mikola, E-mail: pm@mm.unknown
• Kangas, E-mail: ek@mm.unknown
• Heikurainen, E-mail: lh@mm.unknown

Litters of different plant species vary greatly in regard to their nutrient content and other properties. The aim of the study was to compare different litters from the standpoint of their value as soil fertilizer. In an experiment Scots pine (Pinus sylvestris L.) seedlings were grown in pot cultures in which known amounts of different litters had been mixed with the soil. The tested litters were Pinus sylvestris (L.), Larix sibirica (Ledeb.), Betula sp., Populus tremula (L.), Alnus incana (L.) Moench, A. glutinosa (L.) (Gaertn.), Sorbus aucuparia (L.), Tilia cordata (Mill.), Acer platanoides (L.), Corylus avellana (L.), Eupteris aquilina (L.), and Deschampsia flexuosa (L.) Trin.

A striking difference was found between alder (Alnus sp.) leaf litter and all the other litters tested. The difference can be seen from the second growth season on, becaus the young seedling uses mainly the nutrients included in the seed. The leaf litter has mainly unfavourable effect on the growth of the pine seedlings. Only both alder species improve the growth. This is mainly due to the nitrogen content of alder leaves. Tree leaves and other forest litter are often composted in the forest nurseries. It seems that adding nitrogen to the compost is necessary, otherwise compost added to the soil may have a harmful effect on the seedlings. Alder, on the other hand, has nitrogen binding Actinomyces growing in symbiosis in its root nodules, and is able to utilize atmospheric nitrogen.

The PDF includes a summary in Finnish.

• Mikola, E-mail: pm@mm.unknown

Wood consumption in Finland in 1938-1939 was studied by investigating the wood consumption of aprroximately 2,000 farms. One of the surveys connected to the investigation studied fireplaces and heating equipment in rural districts, and recorded the types of fireplaces in the farms.

The majority of the rural fireplaces are rather old-fashioned and the technically best equipment are rare. The fireplaces in Eastern and Northern Finland are often more primitive than in Western and Southern Finland.

In Western Finland, where hard bread is common, the baking oven is lit 30-50 times a year. In Eastern Finland, where soft bread is baked, the oven is lit about 200 times a year. The sauna i heated about 40 times a year in the west, and 80 times a year in the east.

The PDF includes a summary in English.

• Mikola, E-mail: pm@mm.unknown

Birches’ (Betula sp.) ability to grow sprouts is low. The stump grows root collar and stump shoots, but the stump shoots are not proper stump shoots that will grow from the space between wood and bark. The buds are situated very low in the base, even under the ground. In this study, no actual root shoots could be found. Also the bushy alpine birches seem to be formed from stump and root collar shoots.

In Southern Finland silver birch (Betula pendula Roth) is more common than downy birch (Betula pubescens Ehrh.) in dry upland forest sites, while downy birch is common in fresh mineral soil forests and peatlands. In Northern Finland downy birch is the dominant birch species. Of the two species downy birch has markedly better capacity to form stump and root collar shoots both in Northern and Southern Finland. In general, birches grow sprouts much more strongly in Northern Finland.

Growth of the shoots is fastest during the first year after the felling of the parent tree and slows down gradually. The stump shoots may get separated from the stump when the stump decays, and the decay may also spread to the shoots. It is common that the shoots have no own roots, and die along with the stump. The shoots may have own root system or use roots of the parent tree that have stayed alive, in the latter case decay spreads almost always from the stump to the shoot. Whether the tree was felled with axe or saw had no effect on sprouting, probably because the sprouting buds are situated in the base of the tree. The larger stumps had usually fewer sprouts than smaller stumps. The fertility of the site seemed to have little effect on sprouting, but more moist sites formed more sprouts.

Forest regeneration using sprouts may be possible in peatlands for firewood production. on mineral soil sites birch does not suit for coppicing. The proportion of trees originating from sprouts decreases strongly by the time. Consequently, in Southern Finland sprouts have little effect on regeneration of birch. In Northern Finland sprouting is the most important way of regeneration.

The PDF includes a summary in German.

• Mikola, E-mail: pm@mm.unknown

Water extracts of six common soil lichens, Cladonia alpestris, C. rangiferina, C. arbuscula (sylvatica), C. pleurota, Cetraria islandica, Stereocaulon paschale, inhibited growth of ectomycorrhizae of Pinus sylvestris (L.). Of 17 fungi (12 mycorrhizal) tested, many were inhibited while others were scarcely influenced or even occasionally stimulated by the extracts. Cladonia alpestris extract inhibited most fungi while C. rangiferina showed much less influence.

In pure culture synthesis experiments, 32P uptake of Pinus sylvestris was significantly reduced by C. alpestris extract. Different species of fungi showed widely variant abilities to pick up 32 P. in nursery experiments, much more vigorous growth of P. sylvestris and Picea abies (L.) H. Karst. was obtained on plots without C. alpestris than on paired plots covered with it. Betula verrucosa (B. pendula Roth) showed no difference. Under natural forest conditions, P. sylvestris seedlings grow much more rapidly where C. alpestris had been eliminated by road building or reindeer grazing than do seedlings only one meter distant under undisturbed C. alpestris cover. It is suggested that by properly controlled reindeer grazing, establishment and early growth of P. sylvestris on Cladonia sites can be much enhanced. By the time that C. alpestris could become re-established the pine seedlings would have grown large enough to suffer little from reindeer grazing. This study shows the continuity of the major components of the forest tundra biome – the dependence of pines, mycorrhizae, lichens, and reindeer and their predators (human or otherwise) upon each other for a healthy existence.

The PDF includes a summary in Finnish.

• Brown, E-mail: rb@mm.unknown
• Mikola, E-mail: pm@mm.unknown

This paper is a report of the authors visits to over 80 forestry nurseries in 20 countries mostly in the tropics or subtropics. The article aim is to describe the methods used in the various countries and compares them to the conventional methods of cool and temperate countries. The article introduces nurseries of Africa south of the Sahara, Mediterranean area, Australian and New Zealand and Latin America.

A complete revolution has taken place in the Finnish nursery practice, which used to raise the seedlings in natural field soil in open-air nurseries. The seedlings were usually transplanted into transplant beds at the age of two years. Now the use of plastic greenhouses of light construction and an artificial soil substrate (fertilized peat) are essential. The new technique has some similarities to the practises of the tropical and subtropical nurseries. In Finland cultivation in greenhouses has hastened the development of the seedlings and shortened the nursery rotation from four to two years, and provided better control of watering and fertilization.

Peat beds in greenhouses are used also in Swaziland. The advantage of peat is that it is free of weed seeds, which eliminates weeding. Peat substrate gives also better yield of seedlings, which decreases the need of seeds, which is important in Finland. Another technique common with tropical silviculture is the production of potted seedlings, which are easy to handle and transport. In tropics, peat pots (jiffy pots) have made it possible to grow plantable seedlings in one season without transplanting. The present Finnish technique means a decreased degree of mechanization compared to the conventional technique of modern European and American nurseries.

• Mikola, E-mail: pm@mm.unknown